When should I really stop etching a white spot?

Although they may be pre- or post-eruptive, all white defects of the enamel have one thing in common, which is a histological condition of hypomineralization. The reason why the human eye perceives a white spot lies in a variation of the Refractive Index (RI) of the hypomineralized enamel, in which the mineral phase is severely diminished and replaced by organic fluids having a remarkably lower RI than that of sound enamel.

illustration of light ray ray and white spot in enamel

The appearance of white lesions depends on the physical behaviour of light. For optical reasons, when there is a difference in the refractive indexes (RI) between two phases, i.e. healthy and hypomineralized enamel, a deviation of incident light rays happens at the interface. At each interface, the light is deviated and reflected, staying trapped in an “optical labyrinth” that is over-luminous and therefore perceived as white.

white spots on upper incisors in female smile

Nowadays white discolorations may be treated in a minimally or non-invasive approach, by evening out the RI, while “touching” the tooth as little as possible. The main factors to take into consideration is the depth of the lesions and their position inside the thickness of the enamel.

close up of white spots on incisors

This 25-years-old female patient came to my observation complaining about her smile because of some white spots. She never had an orthodontic treatment, and got some professional bleaching in the last four years. She asked that her white spots be treated in one single session, as she would have been attending her graduation ceremony three days later.

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Photography and transillumination, even with a common curing light, are useful tools to better understand the depth of the defect and choose the right treatment plan. More precisely, when a white spot is crossed by light, meaning the light isn’t stopped at all by it, a micro-invasive restorative treatment can be performed predictably.

style italiano styleitaliano dmg icon brown spot
style italiano styleitaliano dmg icon brown spot
style italiano styleitaliano dentistry

In this particularly case I chose to treat the patient with a resin infiltration technique (Icon – DMG Germany) . Rubber dam isolation is highly recommended, and it was performed in order to have a dry and more comfortable working space, tissue protection, and acceptable retraction.

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After having properly cleaned tooth surfaces, an a 15% chlorhydric acid etching solution (Icon-Etch -DMG Germany) was applied on the involved teeth and rubbed for 2 minutes, with the aim of getting easier access to the hypomineralization. The acidic gel was then rinsed thoroughly and teeth air-dried.

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An ethanol solution (Icon Dry – DMG Germany)  ) is used to perfectly dry the surface. This solution has a refractive index very similar to resin’s one, so it also allows to get a preview of the final outcome. Abundant ethanol is applied and left for at least 30 seconds to allow a better penetration and provide a more reliable previsualization.

drop and spreading of icon dry ethanol solution

This step is crucial because, depending on the result, we decide whether to repeat the process, or start the resin infiltration. In this specific case, I decided to repeat the acid application.

before and after ethanol revisualisation

Before and after second etching, and application of Icon DRY. Although the white spots almost disappeared, I wasn’t fully satisfied, so I decided to repeat the full erosion cycle.

previsualisation before infiltration of white spots

Even the result after the third ethanol application, although close to the expectation, was not fully satisfactory, so a fourth, and last, etching step was required.

teeth wet with ethanol alcohol

I was pleased with this achievement and I decided, therefore, to infiltrate the spots.

icon infliltrant resin syringe

A low viscosity, solvent-free resin (Icon Infiltrant – DMG Germany) is able to penetrate as much as the previously used ethanol solution. Resin infiltration requires 3 minutes application, and rubbing on the tooth surface with a specific tip. Let the resin act to a proper capillary effect.

dmg banner style italiano styleitaliano
dmg banner style italiano styleitaliano
orange floss before infiltration

I flossed to remove the excess and separate teeth not to splint them after light curing.

light curing of resin

Each tooth was polymerized for 40 seconds. This infiltrant step was repeated, letting the infiltrant set again for 1 minute before light curing for another 40 seconds.

eccesso instrument for excess resin removal

Cervical and interproximal resin excess was removed using the Eccesso instrument (LM-Arte powered by Style Italiano).

finishing and polishing proximal strip

Then a polishing strip (3M™ ESPE™ Sof-Lex™) Finishing Strips) was used to polish.

silicone tip for resin polishing

Another critical step is the polishing procedure. Rough resin on the surface is extremely sensitive to the oral environment and staining, so polishing steps are mandatory for the final aspect and long term stability. Here’s the first silicone tip used.

fien-grit silicone tip for polishing

A second silicone tip with a finer grit.

goat brush and polishing diamond paste

Final step: a goat brush with an extra-fine diamond paste, using low pressure and low rotation.

teeth after resin infiltration

Finally the surfaces were polished.

teeth after resin infiltration

Right after rubber dam removal. The patient is really happy about the result.

teeth after resin infiltration and polarised picture

At recall, 3 months later, integration is very good.

smile after infiltration treatment

The smile 3 months after the treatment.

before and after resin infiltration of white spots on central incisors

Before and after.


Maximal outcome with minimal intervention was achieved. The resin infiltration technique can be our first choice when white discolorations are confined in the outer portion of the enamel. Fluorosis (mainly TSIF I, II and III) and white spots due to caries, therefore, are the main indicated hypomineralization to be treated with ICON.
Sometimes more than two etching steps are required to solve the problem. Follow the feedback given from ethanol solution, and remember to let it sit on the surface for at least 30 seconds for a predictable, and reliable preview. Ethanol easily evaporates, but, if the etching step was effective, the preview would last longer. Don’t forget to properly polish because it’s a crucial step for the long-term success.


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2. Denis M, Atlan A, Vennat E, Tirlet G, Attal JP. White defects on enamel: diagnosis and anatomopathology: two essential factors for proper treatment (part 1)- Int Orthod 2013;11:139–165.
3. Fejerskov O, Larsen MJ, Richards A, Baelum V. Dental tissue effects of fluoride. Adv Dent Res 1994;8(1): 15-31.
4. Subramaniam P, Girish Babu KL. Evaluation of penetrating depth of a Commercially available resin infiltrate into artificially created enamel lesions: An in vitro study. J Conserv Dent. 2014;17(2):146-148.
5. Arnold WH, Haddad B, Schaper K, Hagemann K, Lippold C, Danesh G. Enamel surface alterations after repeated conditioning with HCl. Head Face Med. 2015;11:32.
6. Fejerskov O, Nyvad B, Kidd E. (eds) (2015) Dental Caries: The Disease and Its Clinical Management. 3rd Edn. Oxford, Wiley Blackwell.
7. Bhirth G. Management of fluorosis lesions with differing treatment modalities https:// www.styleitaliano.org/managing-fluorosis-lesions-differing-treatment-modalities/
8. Manauta J, Salat A. Layers, An atlas of composite resin stratification. Quintessence Books, 2012.


style italiano styleitaliano indirect restorations with dual-cured dentine substitutes

Simplifying indirect restorations with dual-cured dentine substitutes

Stress-free and beautiful indirect restorations require materials that simplify build-up, ensure complete curing, and facilitate smooth preparation.